District



N. T.A wHITAK'ER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION man APR. 4. 1916. nENEwED FEB.2,1922.

1,429,003. Patentedept- 12, 1922.

3. SHEETS-SHEET L IIIILYIIIIIIAZQIIIL N. T. WHITAKER. TELEPHONE XCHANGE SYSTEM. APPLICATION FILED APR. 4.v |916- HENEWED FEB. 2, 1922.

1,429.003. Patentedsept. 12,1922.

3 sHEETs-sHET 2.

N. T. WHITAKER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 4. I9I6. RENEwED FEB. 2, 1922.

1,429,003'. PatentedSept. 12, 1922.

3 SHEETS-SHEET 3.

Patented Sept. 1 2, 1922.

rieures STATES Noria-MN r. vvfnifrnnnn,

r. Lownnsfr; i

new rome, N. Y., es

SIG-NOR Oli ONE-FGURTH LO HARRY TELEPltUE-EXCHANGE SYSTEM.

Application lled April 4, 1316, Serial No. 88,832.

To all whom 'it may concern;

Be it-lrnoivn that l, NORMAN '.l. lVHiTnnuR, a citizen of the United States, and resident of New York, in the county of New York and State of New Yorlr, have invented new and useful Improvements in Telephone-Ei;- change Systems; and l hereby declare the following to be a full, clear, and enact descriptien of 'the invention., such as to enable others skilled in the art to maire and use the same.

My invention relates to telephone exchange systems and more particularly to signaling system `to enable tvvo connected subscribers to be notified that a certain party desires to be connected with either of them, and further to notify the third party that the line called is busy and has been notiiied of the second desired connection.

It is often the case that when tivo subscribers are conversing on a. Wire that a third person desires to be connected with either of the tvvo who are talking'. n My invention seeks to overcome this bythe provision of signals situated at the subscribers stations, adapted when two of said subscribers are connected, to be controlled through means associated "with the cord circuit ofthe same or a second operator through which the third party Wishes to call the connected parties. A

Another in'iportant obyect of the iir'mti on is as follows: When a party desires to get either of two subscribers who are talking` on a telephone circuit, he is at the presenttime told that the other party is busy. lThis en' tails Work and time lupon the operator and my invention to overcome this by cirectly signalingjsaid p .ity who desires to be connected as soon as the operator herself lrnoivs that the Wanted party is busy. No new signaling` means is used, simply the means which my system already provi des for With each and every telephone.

My system has certain desirable results as follows: .t would be an advantage to tivo subscribers when they are conversingv to lrnoiv that some one else desires to talk with them. rlhoy 'would in all probability slierten their conversation to enable the third party Ato get connection. This is furthermore advantageous to the party who desires to tall:

, to thetWo' subscribers, thus preventing much annoyance and .inconvenience when be is told that the wire is busy. Furthemuore, my

Renewed February 2, 1922. Serial No. 533,673.

system is of advantage to thetelephone companies in that they are enabled' to collect more revenue from the pay stations as frequently when one desires to call a party and is told that they are busy, he will simply defer his call to a later time and possibly not call at all. Although this invention appears simple, itrequires great skill to carry out the objects of the invention. `While I have shown apparently complicated means for accomplishing` this much desired object, it would be found to be comparatively simple in construction and operation.

Various signalinga means may be used to attract the attention of the connected subscribeifsthatv some one else desires to communicate with them, but I prefer that the signalling means be made visual as vvill be clearly pointed out, although the two subscribers could be notified by means of an audible signal used in 'place of the visual signal. lhe'visual signaling means could be either in the form of a flashing filament located-in the telephone standard'or nearby or could be by 'means Which l have shovvn which' consists in asemaphore or flag` pivotally mounted on the vtelephone stand which controlled from the central station. l have preferably shown this signaling means connected to the stand of an ordinary telephone but itis obvious that this or other signaling means could be applied to the teleprions structures used in booths or in telephone Wall attachments.

ln reduction to practice, I have found that the form of my invention, illustrated in the drawings and referred to in the above description as the preferred embodiment, is the most eiiicient and practical, yet realizing that the conditions concurrent with the adoption of my device will necessarily vary, l desire to emphasize the fact that various minor changes in details of construction, proportion and arrangement of parts may be resorted to when required, without sac rilicing` any of the advantages of my invention as defined in the appended claims.

Referring` to the drawings in which similar parts referred to by similar reference numerals,

Figure l; represents a front elevation of one form of the subsfni'ibers signaling device.

Fig. 2 is a front View of the signaling' device of Fig. l, With the cover removed.

Fig. 3 is a fragmentary section through the standard' of a desk-set telephone showing a modified form ot signaling device.

Fig. t is a diagrammatic view ot the circuits of a telephone exchange system equipped with my signaling system.

Fig. 5 is a diagram illustrating a modication in which the signal is operated by a reversal of the battery supply current, in the standard Vestern Electric circuit.

Fig. 6 is a similar diagrammatieview of the device applied to circuits of the Kellogg type.

Fig. 7 is a diagram illustrating a circuit arrangement in which the signaling apparatus is actuated upon the testing or' the line.

New referring more particularly to the drawings and especially to Figs. 1, 2 andy 3, I have herein shown the signalingmeans, or

responsive devices to be used at Vthe sub-` stations. In Figs. 1 and 2 I have shown an electromagnetic` responsive device adapted to be used in either ot two modified circuit i arrangements, to be hereinafter described,

provided;- with a cover 2 and adapted to be mounted on` a standard 4L olf a desloset by means `of a split ring member 3, or other suitable attachingl mea-ns, carried by the casing 1i. Mounted within the casing 1 is a pair of electromagnets, 5, 6 having torwardly projecting cores 7, 8, which act on a rotary, polarized armature 9 journaled on i the armature 9 will swing into a vertical positien, positioning the flag as indicated in dotted lines 'in F ig. 1. As the armature 9 is polarized it will rotate in a counter-cloclr wise direction whenthe magnets are energized with a given polarity, but when energized in the opposite polarity the armature will notrotate in a clockwise direction due tothe limited downward extension of the are of the aperture 13 limiting the downward movement of the staii1 12. In operating this maining length ot the connection between the subscribers. However, in a simplified .top thereof and positioned `to enga-ge the top of the statt 12 when the iiag is thrown up into set position.

Reterrii'ig in detail to Fig. 3, I have here shown a portion of the standard of an ordi nary desk set having an aperture 2() inside ol which is mounted a smallk incandescent lamp 21. r1he lamp 21 fits into a socket 22 carried by the bracket 23 which in turn is fixed to the wall of the standard 19 by. a suitable screw such as 211. lheibracket 23 is made circular in form where it contacts with the wall of the standard and carries an annular member 25 whose purpose-is to hold a glass cover 26 over the aperture 2U to protect the light and other parts within the standard from dust.

In Fig. 4 is shown diagrammatically, a circuit arrangement et" the Western Filectric type in which is incorporated a simpliicd form ot ,ny signaling system. In this are shown two subscribers stations C and D. rilhe .line wires 29 and 30 of the subscribers station C terminate in the central exchange in normally closed contacts controlledby the armatures 31 and 32 olf the cut-oil:z relay 33. The cut-oft relay 33 has one terminal connectoii through wires 3a, 35 and 6T to the positive side of the common battery B, while the other terminal of the cut-otf relay' connected to the multiple et the sleeve contacts 33 or' the multiple jacks 79 and Si). The armature ot the cut-oliE relay is connected Vto battery through conductor 3dwhile the armature 32 leads to one teriniiial` oitl the line `relay 33, the other terminal of the line relay being connected to the minus side of the battery by conductor 37. Multiple jacks, two, 79 and 80, of which are here shown, extend :troni the line members 2D and 30 and consist each of a tip contact 31, ring contact 32 and sleeve contact The line relay 36 controls the usual line lamp 33' through a normally open contact of the ar` mature 39. At the subscribers stations thel usual switch hook S, transmitter T, and re ceiver R are provided, the switch hook S` controlling the line circuit through the contact 40.

In addition to the standard subscribens equipment, I provide the signalresponsivc device 43, here shown as a lamp, although I. may also use in its place the electro-inagnetic signal illustrated in Figs. 1 and 2. The signal lt3 has one terminal connected directly to ground and the other terminal connected to the tip side of the line through contacts 41d-, which coi'itacts are adapted to be closed by the bridging nir-anbei 1-5.

The apparatus and circuit arrangement of the substation D are in all respects siniilar to those of the substation C and the preceding description of apparatus and circuits will therefore suliice tor both substations.

The cord circuit here shown is of the stand ard "Western Electric type with the exception that a key 96 is inserted in the calling tip conductor 60, for a purpose to be hereinafter described. rlhis cord circuit consists of the usual answering` and calling plugs, the answering` plug having its tip 55 and ing connected through the right halves and 66 et one side or' the repeating coil, between which is connected the battery B over the conductors 67 and 68. Similarly the tip 56 and ring 58 or' the calling plug,v are connected over conductors 60 and 62 to the other two halves 63 and 64. of the repeating coil.

Included in the ring conductor of the cord circuit are the usual supervisory relays 69 and 70. The relay 69 controls the calling` supervisory lamp 71 through a normally open contact on the armature 721., which contact operates upon closure to connect shunting resistance 7 8 around the terminals of the lamp. The lamp is supplied with current from the battery B through conductor 68, the resistance 72, sleeve Contact 286, the sleeve of the jack 83, through the cut-olii relay 33 and baclr by Way of Wires 34 and 65 to the plus side of battery. The supervisory relay controls the calling supervisory light 74 in a manner similar in every respect to that of the answeringl supervisory relay, the light 74 being supplied with current from the minus side of the battery over conductor 68, resistance 78, conn ductor 97, sleeve contact 285, jack sleeve contact 85, conductor 76, cut-oil relay 50,

nd conductor 35 back to the battery,

T he usual ringing key 86 is provided which is adapted upon actuation te disconneet the cord circuit frein the tip and ring oi the plugl and connect in its place a suit-A able source or alternating` current for ring-J ing purposes. rlhe cord circuit, at the calling` end, 1s also provided with the usual operators listeningand talking set for the purpose oi" conversing with the subscribers and testing;- the 'wanted lines.

rlhe operation of the circuit apparatus in Fig. el: is as follows: rlhe subscriber at substation (l desiring?l a connection with a subscriber D liifts his receiver oft the hooi; whereupon the line circuit is closed over the .following paths: Battery B, conductors 67, 85, Bil, armature 3l, line conductor 29, 42, inchution coil winding ll, switch hook con.- tact 40, switch hook El, transmitter T, con ductor 30, 32, line relay 86 and cozuluctor 87 back to the ininus side oli battery As this circuit inchules the windings olf the line relay 86, this relay is energized attracting its armature 39 and completing the circuit ot the line lainp 38 which notilies 'the operator that a connection is desired. rllhe operator thereupon inserts the ansvveringgA plug in the jiaclr 79 whereupon the current lioivs trein battery B, over conductor 68, resistance 72, supervisory lainp 7l, sleeve contacts 286, 83, cut-oii relay and baclr by Way ot conductors Se and 35 to the positive side el? battery. As this circuit includes the cut-oit relay 33, this relay is energized attracting its arinature and disconnecting` the line Wires from the line relay 8,6 to the battery conductor rlihis in turn opens the circuit of the line relay which releases its ar i ature 39 ertinguithing the line lainp 38. The substation C is new supplied with cur-- rent over the following` paths: Battery B, conductor 68, repeating coil winding' 66, conductor 6l, 57, 82, 30, transmit-ter T, switch hook Contact el), all. 2, back over line conductor 29, jaclf spr 8l, tip contact 55, conductor 59, 65, and baclr te battery through conductor 6T. As the answering supervisory relay 69 is included in the conductor 6l over which this circuit was traced, this relay bef-eines energinen, attractingv its armature 72, which shunts out the supervisory lamp 7l. The operator new actuates her listening' lrey 87 which connects her listening and talking circuit set across the cord conductors 60 and 62r This talking set consists of receiver' 89 connected across the terminals el' the listening key 87 in series with condenser 94 and the secondary Winding); the primary 91 oit the induction coil connected in series with a transmitter 88 and retardation coil 90 across the ter1ninals of the battery. A condenser 93 is connected in shunt ett the Winding` 9i. and trans initter 88. lVith the listening' set in connection the operator inquires the nurnber desired and upon ascertainingl the saine to be that of the subscriber D, inserts the calling; plug); into the jack 77. il circuit is then coml pleted over the following path: Battery B, 68, 78, 74, 97, 285, 85, 76, cut-olli relay 50, conductor 5l, 85, and baclr to battery. As this circuit includes the windings of the cut-olli relay 50 and the light 74, both oi? these are energized, the cut-oll relay 50 actino,i to disconnect the line wires 46 and /l-7 olf the called subscriber troni the battery wire 5l and the line relay 52. The operator nals the called subscriber by actuating the ringing;- key 86 and when the called subscriber answers by risinnj his receiver,y his line circuit is completed over the following path: Battery B, 68, 6ft, 69 58, 811-, d6, through the substation apparatus, back over line Wire i7, jack spring,r 996` 56 6th includ ingr the lrey 96, 68 and 67 te battery ll. )is this circuit includes the 'windings ol the calling` supervisoiy relay 70, this relay is energir/.ed attractingits armature and placing the resistance 7.6 in shunt of the lamp P{4l-and cxtinguishingit. The extinguishing thus indicates to the operator that the called subscriber has answered andthe parties are 5 now connected for conversation` over the circuit indicated in lines.

It while the parties C and D are thus con.- nected for conversation, a third party should desire to be connected with either one of them, the line of said third party would become connected with the cord circuit of a second operator through her answering plug in a manner similar in all respects to that above described. The second operator asi certaining the number desired to be that of the subscriber D, teststhe line of that subscriber by touching the tip, ot the` plug 56 to the sleeve contact ol a multiple jack such as 295. As this line is already connected with, the sleeve contactsot all of its multiple jacks will be connected through the contact 285 of the First operators calling plug to the minus side off the battery, current will flow 'from the plus side of battery over the tip conductor of the second operators cord circuit to the jack sleeve contact 295 and back to the minus side-oi battery by way of the plug sleeve contact ol? the iii-'st operator. This liow of current will vai'y the potential across the receiver 89 of the-second operator giving her a click in the ear which isthe usual indication that the line is busy. Uponv receiving such a signal the operator plugs in to the jack in the usual manner, but insteady of operating the ringing key as usually would have been done had the wanted subscribers liney been idle, she operates the special signaling key 96 which opens the conductor 60 and connects it on the calling side with the battery B. Upon closure ot' this connection, both the signals 13 and 280 at theI stations between connected subscribers will be energized by cur rent flowing over the following circuit:

Substation D from battery B over conductor 60 of the secondoperators. cord circuit, tip contact 56, vtip contact of the multiple jack 295, line conductor 47, switch hook contacts 281 and through signal 280 back to battery by way of ground, while 'lfor the substation C the current will branch at the jack 77 of the lirst operator passing therethrough by way of tip contacts 296, 56, of the operators cord circuit, tip conductor 60, including the normally closed contact of key 96, repeating coil windings 63, 65, 59, 55, 79, 29, signal contacts 441-, substation signal 43 and back to battery B by way of grou-nd. It will thus bessen that each time the secondoperator operates the key 96 the lamps 43 and 280 will be flashed, and if theelectromagnetic signal device oit Figs. 1 and 2 is used in place of the lamps, only a single momentary operation oil? the key 96 will be necessary as the first actuation of the signal.

will cause it to remain in set position until restored by hand. It is further to be noted that it it is desired to use the lamp, and still obviate the necessity ot the operator having to operate the key96 more than once or for any considerable time, the light may be combined with the device of Figs. l and 2, using the latter device as a relay to control the local circuit for the light. In such case, it is only necessary for the second or testing operator to momentarily actuate the key 96 atteny which she may withdraw the plug and wait until the third party again initiates a call either through her or any other opcrater. It might be noted in passing that with the batteries B and B connected in opposition or multiple here shown, the tip conductor oit each line will be used in common by both the talkingcircuit and the signaling circuit, which arrangement is the preferable one. However, it would not al:- fect the operation of my device to reverse the polarity ot the battery B.

Referring to Fig. I here show a modified method of control adapted to the lVestern Electric type of circuits. In this ii'orm olf the invention, an electrofmagnetic actuated, polarized signaling device is used at each substation inserted in oneotf the line conductors. To operate the signals at the substations ol` the subscribers, it is only necessary to reverse the current in the line and Jfor this purpose I have shown a simple lorm of polechanger relay 140 associated with the operators tordr circuit, although it is to be understood that various other means ot reversing the current may be used, such forinstance as that shown in the patent to E, Thomson, No. 1,121,953 issued Deccm ber 22, 1914, or to (i. Babcock, No. 1,012,793, issued December 2G, 1911, such imparatus being either connected in place oi? the relay lll-ll or controlled by ar relay in its place. rIlhe line circuits and terminal apparatus therefor are of the well known standard type and therefore need no descriptionr` except to point out that the special polarized signaling means at each substation is insentedy in one ot the line conductors, tor example, here shown in the tip conductor with a condenser bridgedV across its terminals to compensate for any inductance in the windiiiigs ot the electro magnets. The relay 14() is provided with, a pair olf connected movable contacts or armature constituting the movable members oit a pole changer, uf'hich arn'niitures 138, 139 are connected directly to the terminals oit the battery B2 over conductors 143 and 107, respectively. The inner contac of the pole changer are connected togf-ither in the usual manner and lead through conductor 13G to the middle point of the upper windings o'l` the repeating coil, vwhile the outer contacts are connected together and lead through conductor 137 to thc middle point of the lower windings ot' the repeating coil. 1n addition to the relay 140 the only other changes neces sary in the standa rd circuit. are to substitute the windings o1lv the relay 153 for the perinanently connected resistance in the circuit ol' the calling supervisory lamp 150 and to add an extra pair ot contacts on the calling supervisory relay 1&9. The relay 140 is primarily controlled by relay 153 through a normally closed contact thereof. The ini. tial energizing circuit ot the pole changer relay 140 may be traced troni battery l over conductors 10i'. 106, 302, armature 1511, conductor 155, windings ot' relay 140, conductor 158, armature contact 297 and bach to the grounded side oit battery B2 by way ot conductor 1011. As this circuit includes a normally open contact controlled by the calling supervisory relay, the circuit ot the pole changer relay will be maintained normally open and out ci control of the relay 153 until after the called subscriber has answered, and as the circuit of the calling supervisory light, which in this case includes the windings of the relay 153, is always closed immediately upon the-insertion ot the calling plug and betere the subscriber answers, the circuit of the pole changer relay will be opened at the contact ot relay 153 before it is closed through the contant 297 by the actuation of the calling :nipervisory relay by the called subscribers act ot litting his receiver. At the end ot a conversa tion when the .called subscriber linally hangs up his receiver, the calling supervisory relay will be cle-energized, thus opening the circuit ot the pole changer relay at Contact 297 betore it is closed at contact 154 which would not occur until the operator with draws the calling plug.

1n addition to the electrically controlled apparatus here shown in the cord circuit, there is associated with cach opera-tons cord circuit a special signaling key 165. normally open and connected between the free side ot battery B2 and the conductor 164i ot the calling supervisory circuit by way ot conductors 16T and 166 respectively, The function of this lrey is to control the pole changer relay associated with another cord circuit, `when the cord circuit with which the key is associated is connected with any one ot the nniltiplc jacks oit cit-her oli two subscribers interconnected through the said other cord circuit.

lhc eilect oit the closure ot the special key 165 is to short circuit or `shunt out the wiiulings ol.t its associated relay 153 and that of the other operator already connected with the saine wanted line. rlhis shunt circuit will. be described in detail in the course of the operation which follows.

In operation the subscriber at substation E desiring` a connection with a subscriber at substation l?, signals the operator by raising his receiver from the switch hoolfwhich closes his line circuit and actuates the line relay .105 in a manner similar to that described in connection with Fig. and the operator perceiving the signal inserts the answering plug 126 in the jack 110 which energizes the cut-ott relay 102 extinguishing the line signal. The operator then actuates her listening lrey and ascertaining the number desired to be that ot' the substation F inserts the calling plug 127 in the jack 124v whereupon the out-ott' relay 119 is connected in series with the calling supervisory lamp 150 and relay 153, this circuit being traced as follows: Battery B2, 107, 106, 302, 153, 150, 164, 161, 163, 119, 120, 367, and 104 back to the grounded side of battery B2. This circuit ener` gizes the relay 153, lamp 150 and cut-ott relay 119. The energization of relay 153 opens the circuit of the pole changer 140 at contact 1541 and the energization of the cut-oit relay disconnects the called line from the line relay 121. The operator then actuates her ringing key to signal the called subscriber in the usual manner, and when the called subscriber answers by raising his receiver from the switch hook his line circuit is closed energizing the calling supervieory relay 1419 which partially closes the circuit or the pole changer relay at contact 197 and shunts out the calling supervisory lamp through resistance 152 and contact 151. The extinguishing ot the calling supervisory light indicates to the operator that the connection has been completed and leavesher free to attend to other calls. The energizing circuit ot the calling supervisory relay 1419 is included in the battery supply circuit ot the called subscriber which may be traced as follows: Battery B2, 107, 142, 139, 137, 135, 1119, 131, 115, through substation F by way oli a transmitter, switch hook, induction coil winding,magnet windings of the special signal 301 and back over line wire 116, tip conductor 129, 133, 136, 138, 143, 103 and 104, hack to the grounded side of battery. Although this circuit includes the windings ot the special signal 301, the signal is not actuated at this time as it is so connected iu the circuit that the polarized armature will tend to turn in the opposite direction to that .in which it is designed to turn in order to effect a signal. Now, should a third subscriber attempt to obtain a connection with either one oit the subscribers, Yfor example subscriber F, such third party would obtain a connection with a second operator through her answering plug, corresponding to 126, and the second operator ascertaining the number required to be that of the substation F will test one ot its multiple jacks, such as 125, at her position and finding the line busy will insert her `calling plug, corresponding to the plug 127, into the multiple jack 125, and instead of actuating the ringing key 1.58 she would have done had the line not been busy, she operates the special signaling key 165. This last act oit the second operator, connects the free end ot the common battery B2 to the right `hand terminal 'ot the relay 153 oit the first mentioned operatoi"s cord circuit, over the following paths: Battery B2, 167, 166. 164;, of the second operators cord circuit, imultiple jack 162, 163, 161, thence through the `first operators cord circuit over conductor 1641. resistance 152 and the lamp 150 in parallel to the right Vhand terminal 0'1": relay 153. As the other terminal of relay 153 is permanently connected to the free side of battery `BL bv Way of conductors 302 and 107, this relay together with the lamp 150 are shunted `out of circuit so long as the key of the second operator remains closed which is momentary. The relay 153 ot the first mentionedoperators cord circuit thereupon becomes cle-energized releasing the armature 154 and completingl the initial energizing circuit of the pole changer 'relay 140, over `the following path: Battery B2, 107, 70, 302, 154, 155, 1110, 158, 297 and back to ybattery B2.

-Energization of relay 140 causes it to attract it pole changer armatures 139, 13S and the locking armature 157. 'Ihe locking `armature closes va locking circuit tor the pole changer relay as follows: tree side of battery B2, 107, 157, 156, 104, 156, 297 and back to the grounded side of battery B2. Thus, after the second operator releases the key 165, removing the shunt from relay 153 and allowing it to again be-l come energized, the initial 'energizing circuit of the polechangerirelay is again open at contact 154i-, the relay remaining energized through its locking circuit. The operation of the polegchanger contacts 130, 138 reverses the direction ot the battery supply circuit in both of the inter-connected lines E and yF, and as cachot the polarized signaling devices 301and 303 are each ineluded in the battery supply circuit oi its substation, these signals are actuated. their parts being adjusted to respond to this change in direction o'l the supply current. The subscribers E and li, perceiving the actuation. 'of their signals, will. then, il" the present connection is not an urgent one, hang up their receive-rs and await the calling of the third party. It. on the other hand, the subscriber fIl is the party wanted by the 'third party, the second operator responding to the call of the third party would have inserted hercalling plug corresponding to 127 vin one oit the multiple jacks such `as 111 ot the substation "E, and actuating her key 165 wouldhave shunted out the relay 148 at the answering end of tlc lirst operato1"s cord circuit. In such case, the relay 1418 upon de-enelgization causes the initial energizing circuit oit the pole changer relay to be completed over the lfollmving path: tree side ot battery B2, 107, 70, 302, back contact ot relay'MS, 155` 140, 15S, 207 and back to the grounded side of battery B2.

The pole changer relay energizing, locks itself and effects a reversal ot the battery supply circuit of the inter-connected subscribers, E, F, in the same manner as that before described. At the end of the conversation when the subscribers E, F hang up their receivers, their line circuits open and the first operator is given the disconnected signal in the usual manner through her supervisory lamps, and the calling and answering plugs 126 and 127 are withdrawn. lithdrawl o1 the calling plug 127 opens the circuit through the ring cord conductor 131, thus (le-energizing the calling supervisory relay which opens the circuit of the pole changer relay at armature 297, whereupon the pole changer relay istie-energized, and the circuits restored to normal. It will thus be seen that the only act required of the operator to actuate the special signal devices of the inter-connected parties, isto` insert the plug atter testing `and actuate her special key 165, after Which he may take down the connection as is usual, upon linding the wanted line busy. l

In the modification shown in Fig. 6, the operati on and circuit arrangement are similar to that described in4 F 5 except that the system is here shown adapted to the Kellogg type of cord circuit in a two-wire, multiple, common battery system. In the use of this arrangement the subscribers substation apparatus may be identically like that of Fig. 5. The change necessary to adapt the system to the Kellogg cord circuit is to add tbe pole changer relay 213, an extra armature on each of the lintttery supply relays 204, 205, 216, 217, and the special signaling key 233. In this, as in the foregoing arrangement, the pole cllanger 'relay 213 is provided with an armature 22 and a pair o'f pole changer armatures 211 and 212 and is connected to be controlled. by the battery supply relays in a manner `which will be clearly set forth in the description, and operation.

As the circuit arrangenilent and oi'ieration ot the standard. Kellogg cord circuit is-well known in the art, it is not deemed. neces sary to here describe the same indetail.

The operation of the arrangement of Fi g. 6 is as follows: The subscriber G desiring to make `connection with line H, raises vhis receiver from the switch hook, closing the line circuit in the usual manner, which energizes the line relay `173 by current flowing frein the 'free side ol' batteiiy li over 2252, 17%, lf3, baclr contact oit cut-oll' relay arma ture 172 over line Wire 17 0 back over line Wire 169 through armature 171. oilthe cutcii relay` to ground and liairnk to l,-;-itterv B3.

Energization. or" the line relay actuates the line lamp 180, and the operator iierceivinun the signal inserts her ansrvering,r plug; 129 into the calling jack 182 et the line G', Where-- upon the cutoff relay .is energized by current flowing from the tree side of battery B over 215, 212,210, 209, 205, 291, 18d and through cut-ott' relay to ground and back to battery. The cutoff relay attracting' its arn'iatures opens the operatorie cord conductors 200, 201 directly across the line 170, 169. The operator ina-y now converse with the calling' subscriber over any Well known :torin oil? listening' set not shown, and ascervhe nuinber Wanted to be that ot the l Ae lil, will insert her calling` plug into one of the multiple jaclrs. such as 193, of the line H, whereupon the line relay 299 will be energized in series With the sleeve supply relay 217 in a inanner similar tei that described tor the eut-oli1 relay 198. The operator then signals the called subscriber in the usual manner and when. he answers by raising,` his receiver the line circuit H is closed and the lines (l and H are connected tor con.- yersati-on over the circuit in zicd in lieaxfv lines. The battery supply :uit tor the calling` line G may be traced .troni battery B3, Overname, 21o, 209,205, seine/i, ies. 171 over line Wire 169 -to the substation and. bacl; over line Wire 170, 172, 183, 290, 200, and tip supply relay 204;, 20' 21.1, 214;, and through `ground to battery ll The battery supply circuit ot the line tlf muy be similar ry traced through the answering side oiV the cord circuit, which, of course, includes the 'tip and sleeve battery supply relays 216 and 217 respectively, It While the lines G and ll are thus inter-connected, a third. party should attempt to get connection with either one ot them, `for exainikile the .line lili, second. operator `would become ronuecfed. with the said third party through the answering side ot her cord circuit which would be identically the saine as the one slioivn and supplied trom the coininon battery l. 'llie second ogierator would then lest one oi the multiple jacks oft the line li and ludiun' the line busy would insert her calling' pliu; and momentarily close the sjiccial. signaling;` key 233. The closure ol Vthis key will coni'iect the tree side ot battery to he right hand terminal of' the sleeve battery supply relay 217 oit the first opera tors cord circuit by Way ot conductor 232.r L31., resistance 234-, contacts ot lrey 233 and sleeve contact of the second operators cord circuit and thence by Way ot sleeve contact 185 et a multiple aclr through the first opeiiators cord circuit over the sleeve condoctor 201 to the right hand terminal of, the battery supply relay 217. As the otlie ter" ininal of this relay is connected directly to the free side oi' battery by way ot conductor 209, 210, 212 and 215` it will be shunted out of circuit and become de-eiier- `gif/red. De-energization ot this relay 217 ol the first operators cord. circuit u'ill cause the armature 221 to be retracted, completingI the initial energizingl circuit ot the pole chen ge" relay 213 over the following path t tree side oit battery lil, 215, 213, 220, 221, 219.. $552.52. and back by way oi :around to bat* 'lhe pole changer relay energizing l locks itself through armature 222 in the lollou ing; circuit: tree side ot battery B3, 215, 213, 22S-l, 222, 219, 323, 21S and bac-lr to the grounded side of battery. The pole ch anger relay will thus remain energized over this lool' fg' circuit atter the key 22;?) of the second op "ator is released and the sleeve battery supply relay 21T of the first operator is agaii'i energized. The energization et the pole changer relay associated With the cord circuit of the first operator reverses the direction ot the battery supply current over both of the previously inter-connected lines G and l-l, actuating;` the polarized signaling devices at the respective sub-stationsv` all in a manner similar to that previously described for Fi 5. Had the third party desired connection with the line (i, the second operator would have inserted her calling plugr into one et the inultiple jacks of the line G, such es 186, and actuating' the ley 233, would have caused the de-energization of the ansiverino ply relay 216 of the lirst operator the re-v versal oi the current in the inter-connected lines Vwill be maintained untilv the subscrib ers hang; lup their receivers and the cord circuit is discoi'mected 'troni the jacks, wher upon the circuit oli the tiparelay 216 will be opened at the tip contact 292, and this relay del-enerqiring;- will cause the circuit ol' the pole changer relay to be opened at the trout contact ot its armature 323, thus restoring; the circuits to normal.

It is to be noted that with the circuit arrangement of both Figures 5 and 6 the pole changer relay of the second operators cord circuit is also operated When she actuates her special signallrey in amanner similar in all respects to that described for the operation and the use of a nornially Cle-energized mi et the pole changer ol the i'irst operator?? cord circuit. rlliis results, ol" course, in a reversal the current supply through the second. @pei itors cord circuit and a consequent actuation oli` the special signal at the substation ot the third party, indicati'nnj` to said third party that `the party called is busy and has been notified that a third party is calling. As the pole changer relay becomes (le-energized upon the withdrawal ell the calling` plug, the signal to the third party endures only so lone as the o pe al'or's calling; plugis in the jacli, ailier which the si) nil. is restored to norn'iafl and the third. party may, il? he so desires, call tor aimtlier nuinber without having` to hang;` up his receiver to get another operator.

The modification shown in lilo". 7 malien use ol the saine genera-l circuit ai'rangement, that is, the lNestern Electric threewire multiple common battery sysrem, the flil'lerences existing; only in the cord circuit, the line circuits remaininje;` identically the saine. This difference in the cord circuit ce siste in the omission of the special signilin-r;-` hey when connected in series with the cut-oil relay 243, asis the case during.' the inter-- connection oit two lines through the nord circuit under normal conditions.

In the use of this type or cord circuit. the operator always, first, tests the called line by touching;- the sleeve conductor l with the tip ot her callin plug 300, which, it the tested line is busy, will give her the usual busy signal through her listeniiuf; set in the saine manner as that described loi. Figi. 4.. At the moment ot this test, the grounded side o'l' battery is connected to the sleeve contact 240 tl'irounh the low resistance oli the winding 245 of the repeat coil, and I take .advantage et this te operate the marginal relay in the cord circuit of an operator previously connected with the same line, in the manner which will .be clearly understood 'lrom the description ot operation as loll o ws A ssuminir that the cord rifircuit here shown has its answering and callinuplugs inserted into the aclrs represented by the sleeve contacts 235 and 240 respectively, and that the called subscriber has answered, the super-- visory relays 260 and 261 would be energized in the battery supply circuits of the respective lines, while the cut-oft relays 237 and 243 will be energized each in series with its associated marginal relay and lamp shunting resistance. The current at this time passing ythe cut-oil' relay 243,

through each cut-oll` relay will not be suflicieut in. volun'ie to energize the marginal relay. Thus under the condition just described the initial energizing circuit of the pole changer relay will be opened at the liront contacts olE the marginal relays 265 and 269, and partially closed at a` front contact el the arunitine 273 ot the calling' supervisory reW lay 26'l. However, upon the testing` of one el? the multiple jacks, such `as 241, of one ol the interconnected subscribers by a second operator, the winding of the eut-olf relay 243 will be `shunted by the low resistance windiup;` 245 ot the repeat coil of the said second operator, the shunt heine,v as follows: right hand terminal oit cut-Orl'z relay 24.3, ground conductor 233, then wire 255, 253,250, 247, repeat coil winding 245, tip condruvtor 253, tip contact 30() of the second operators call ing;` plug, and thence to the lett hand terminal ol." the cutoff relay by way of the multiple sleeve contact, such as 241, and mul riple This shuntingout of the cut-oil' relay will effect an increased flow of current througgjh the marginal relay 269 of the first operators cord circuit and for which increased llow the said marginal relay is adjusted. The increased circuit through the marginal relay is as follows; battery B4, 254, 240. 269, lara-.aching through 266 and 267 to conductor 273 et the first operator, and there over through ring contacts 277 and 240, multiple 242, and again branching through cutoli relay 243, conductor 238 to `ground and through the multiple jack sleeve 241 through the tip side of the second operators cord circuit to ground by way of tip contact 300, tip conductor 25S, 245, 247, 250, 253 and 255. .llnergization of the marginal relay completes the initial energizinfblr circuit of the pole changer relay over the following path: ha ery Blf, 254, 238, 240, 270, 271, pole changer relay 251, 272, 273, and back to the `rroun ded side ot battery `by way of ccnduclor 239.

The pole changer relay energizing locks itself in the following circuit: B4, 254, locking; armature 274, contact 27 5, 251, 27 2, 273 and loaclr to the grounded side of battery by way of conductor The pole changerre lay being thus locked will remain energized after the second operator removes the tip ot her calling plug` trom the sleeve contact of the multiple jack, resulting,T in the removal. ot the shunt from around the 'windings oil" and consequently the (leenei'gization ot the marginal relay269 ot the previously connected operator.. The en.- ergrization of the pole changer relay also et fects a reversal. of the direction of the battery supply circuit in both of the inter-connected lines, through the attraction of its pole changer armatures 249-250, in a manner similar in all respects to that before described for the modification of Fig. 5. Had

nfl-senos the second operator tested a multiple jack, such of the calling subscriber, the marginal relay 265 oiI the previously connected operator would have been actuated in amanner similar to that of the relay 269, completingthe initial energizing circuit of the pole changer relay through its liront or normally open contact and conductor S-0, the remainder of said circuit being over the same path as previously described.

Bitter tie inter-connf-ctecL subscribers hang up their receivers, and the operator withdraws her plugs, the calling supervisory relay becomes (le-energized in the usual manner, opening the circuit of the pole changer relav at a front contact on the armature 273, thus cle-energizing the pole changer relay and restoring` the circuits to the normal condition shown in the diagram.

From the foregoing description, taken in connection with the accompanying drawings the advantages of the arrangement of circuits and apparatus and the method of operating, will be readily understood by those skilled in the art to which the invention appertains, and while I have described the principle of operation together with the device which I now consider to be the best embodiment thereof, I desire to have it understood that the device shown is merely illustrative and that such changes may be made as desired as fall wit-hin the scope of the appended claims.

Vhat I claim is:

l. In a. telephone exchange system, a plurality of substations and talking circuits therefor, connecting links for inter-connecting said substations, means individual to the links operable when connected through its associated link with any one of a plurality of lines already connected through another link to produce current changes in all of said inter-connected lines, and signaling means at said substations responsive to said current changes operable during completion of thetalking circuit of its associated substation.

2. In a telephone exchange system, a plurality of substations and talking circuits therefor, connecting links -lor inter-connecting said substations, means individual to the links operable when connected through its associated link with any one of a plurality of lines already connected through another link to produce current changes in all of said inter-connected lines, and signaling means at said substations responsive to said current changes operable during completion of the talking circuit ol its associated substation, together with other signaling means individual to the said substations for initially signaling the subscribers,

3. In a telephone exchange system, a central station, a plurality of substations, line circuits connecting said substations with ot saitY links operable to vary the current s 1rplied to the lines through its associated l corniroL means associated with each the cui nt- Aink through signaling means at said substaticns responsive to the variation in current produced by said current-controlling means ll. In a telephone exchange system, a central station, a plurality et substations, line circuits connecting said substations with said central station, multiple contacts at the central station associated with each oi said lines, connecting links at the central station cci-operating with said mu tiple contacts 'for inter-connecting the lines, means tor supplying current through said connecing links to the lines connected therewith, current reversing` means associated with said links for reversing the current supplied to a lino through its associated link, control means associated with said links tor controlling the current reversing means associated with any other link through said multiple contacts, and signaling means at said substations responsive to a reversal ot current in the line.

5. In a telephone exchange system, a central station, a plurality ot substations, line circuits connecting said substations with said central station, multiple contacts at the central station. associated with each ol lines, connecting` links at the central station co-operating with said multiple contacts for inter-connecting the lines, means for supplying current through said coi'inecting links to the lines connected therewit i, current reversing means associated with said lines for reversing the current supplied to a line through its associated link, control means associated with said links for Controlling the current reversing means associated with any other link through said multiple contacts, signaling means at said substations responsive to a reversal ol' current in the line, and means for maintaining said reversal of current during the closure of the line circuit.

6. In a telephone exchange system, a central station, a plurality of substations, line circuits connecting said substations with said central station, multiple contacts at the central station associated with each of said lines, connectinglinks at the central station co-operatin g with said multiple contacts :tor inter-connecting the lines, means for supplying current through said connecting links to the lines connected therewith, current reversing means associated with said lin is for reversing the current supplied to a line through its associated link, and operable upon the testing olf a line with Which its associated link is connected and signaling` means at said substation responsive to a reversal or current in the line.

i'. ln a telephone exchange system, a centrai station, a plurality oi substations, line circuits connecting said substations With said central station, multiple sets of contacts at the central station, associated with each ot said lines, each set comprising line contacts and a test Contact, connecting links at the central station co-operating With said multiple contacts for inter-connecting the lilies, means for supplying current through said connecting links to the lines, a test circuit connected with the test contacts or' each line containing a resistance adapted to be shunted upon the testing oi.z the associated line, an electrically operated pole changer associated with each link operable to reverse the current supplied to a line through its associated link, a control relay for said pole changer associated with each link having its energizingcircuit included in the test circuit of a given line when its associated link ris connected with the said given line, said relay and said resistance being so adjusted that the relay will. become energized only upon the shunting of said resistance and signaling means at said substations responsive to a reversal of the said supplied current.

8. ln a telephone exchange system, a plurality of substations and line circuits therefor, links for inter-connecting the lines, a source oi current supply Yfor said lines adapted to be connected therewith through said links, a pole changer associated with each link and operable to reverse the current in the line supplied through its associated link, a test circuit ifor each line, testing means associated with each link adapted to co-,operate With said test circuits and produce current changes therein, a relay associated With each link controlling the said pole changer and responsive to current changes in the test circuit of the line With Which its associated link is connected, and signaling means at said substations responsive to a reversal of current in the line.

l). In a telephone exchange system, a plurality of substations and line circuits there- `for, links for inter-connecting the lines, a test circuit `for each line, testing means associated with each link adapted to cooperate with said line test circuitsl and produce cur"- rent changes therein and in the test circuit oi' a link connected therewith, a relay associated with the test circuit of each link responsive to current" changes therein and operable to produce current changes in the linesinter-connected through its associated link, and signaling means at said substa- .tions responsive to said current changes in their respect-ive lines.

10. In a telephone exchange, aplurality oit substations, talking apparatus ateach substation, and signaling means at each substation, the signaling means of a given substation being operable upon vthe connection of a third substation Withsaid Vgiven substation when said given substation is busy.

11. In a telephone exchange system, a central office, substations, means for interconnecting said substations and means asso'- ciated with said interconnecting means op# erable upon the connection of a third substation With any one of a pair of substations already connected to signal a plurality of said connected substations independently of said talking apparatus.

NORMAN T. WHITAKER. l 

